Comparison of the dental anomalies found in maxillary canine-first premolar transposition cases with those in palatally displaced canine cases

Aim: To compare the developmental dental anomalies associated with maxillary canine-first premolar (MxCP1) transposition and those of palatally displaced canine (PDC) with each other and with the background prevalence in the Maltese population in order to elucidate whether the two conditions have similar or differing genetic backgrounds. Materials and Methods: Dental records of 477 subjects with PDC, 57 subjects with MxCP1, and a control group of 500 subjects with no history of a PDC or tooth transposition were compared for canine eruption anomalies and hypodontia. Results: A high frequency of bilateral occurrence was present for both canine malpositions and when unilateral, a trend to right-sided occurrence was evident. The occurrence of transpositions in the PDC group and of PDC in the MxCP1 group was higher than expected. The prevalence of incisor hypodontia was significantly higher in subjects with PDC and MxCP1, as compared to the control group. Limitations: The size of the MxCP1 group is relatively small. The study population is a small isolated Caucasian population and the results may not be applicable to other populations. Conclusions: There is no significant difference between the MxCP1 and PDC groups in the prevalence or distribution of hypodontia and each of these groups exhibits a higher prevalence of the other canine anomaly. These findings support the theory that PDC and MxCP1 form part of a group of interrelated dental anomalies that share a common genetic basis.